1. Field of the Invention
The present invention relates to sensor systems.
2. Description of the Related Art
An example of sensor systems is a sensor system using a sensor integrated circuit (IC) described in Japanese Patent No. 5474018 (JP 5474018 B2). The sensor IC described in JP 5474018 B2 includes two sensors, analog-to-digital (A-to-D) converters, and a digital signal processor (DSP). The two sensors detect the same physical quantity such as a magnetic flux and each output an analog value according to the detected physical quantity. The A-to-D converters convert the analog values received from the two sensors to digital values. The DSP performs a predetermined computation of the digital values received from the A-to-D converters. The sensor IC transmits the digital values received from the DSP to a communication target via a communication circuit.
By using the sensor IC described in JP 5474018 B2, the communication target that receives digital values can obtain, e.g., first and second digital values corresponding to output values of the two sensors from the sensor IC and detect abnormality of the sensor IC by comparing the digital values. However, in the case of using this configuration, abnormality of the communication circuit may not be able to be detected if the communication circuit transmits the first and second digital values with the same frame configuration to the communication target. For example, if the communication circuit has such abnormality that bit information of a specific data bit in each frame is fixed to zero or one, the first and second digital values that are transmitted from the communication circuit are abnormal values. However, since abnormality occurs at the same location in the frame including the first digital value and in the frame including the second digital value, the first and second digital values that are abnormal values may be the same value. The communication target therefore cannot detect the difference between the first and second digital values when comparing the first and second digital values with each other, and thus the abnormality of the communication circuit may not be able to be detected.